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<h1><a href="https://archiveofourown.org/works/26941345">Thicker Than Water</a> by <a class='authorlink' href='https://archiveofourown.org/users/lady_ladybug/pseuds/lady_ladybug'>lady_ladybug</a></h1>

<table class="full">

<tr><td><b>Category:</b></td><td>Original Work</td></tr>

<tr><td><b>Genre:</b></td><td>Ahegao, Anal Fingering, Anal Sex, Asphyxiation, Bestiality, Dead Dove: Do Not Eat, Debauchery, F/F, F/M, Female Ejaculation, Hardcore, Hypersexual, Incest, Masochism, Mindbreak, Mindfuck, Multi, Other, Parent/Child Incest, Public Sex, Semi-Public Sex, Sibling Incest, Squirting, This is messed up y’all, Ultra Hardcore, Unsettling, Vaginal Fingering, Vaginal Sex, i don’t know how far i’ll go with this but yeahhhh</td></tr>

<tr><td><b>Language:</b></td><td>English</td></tr>

<tr><td><b>Status:</b></td><td>In-Progress</td></tr>

<tr><td><b>Published:</b></td><td>2020-10-11</td></tr>

<tr><td><b>Updated:</b></td><td>2020-10-11</td></tr>

<tr><td><b>Packaged:</b></td><td>2021-05-18 02:36:47</td></tr>

<tr><td><b>Rating:</b></td><td>Explicit</td></tr>

<tr><td><b>Warnings:</b></td><td>Graphic Depictions Of Violence, Underage</td></tr>

<tr><td><b>Chapters:</b></td><td>1</td></tr>

<tr><td><b>Words:</b></td><td>1,208</td></tr>

<tr><td><b>Publisher:</b></td><td>archiveofourown.org</td></tr>

<tr><td><b>Story URL:</b></td><td>https://archiveofourown.org/works/26941345</td></tr>

<tr><td><b>Author URL:</b></td><td>https://archiveofourown.org/users/lady_ladybug/pseuds/lady_ladybug</td></tr>

<tr><td><b>Summary:</b></td><td><div class="userstuff">
              <p>Mary and Katie Sullivan have always been inseparable. Wherever her older sister goes, Mary will follow.</p>
            </div></td></tr>

<tr><td><b>Relationships:</b></td><td>Original Female Character(s)/Original Non-Human Character(s), Original Female Character/Original Female Character, Original Female Character/Original Male Character</td></tr>

<tr><td><b>Comments:</b></td><td>15</td></tr>

<tr><td><b>Kudos:</b></td><td>115</td></tr>

</table>

<a name="section0001"><h2>Thicker Than Water</h2></a>
<div class="story"><div class="userstuff module">
    
    <p>
  
</p>
<p> </p>
<p>This isn't the first time Mary has seen her sister in such a state: on her back, half-in/half-out of the driver's seat in a busted old car parked in the dilapidated remains of an empty storefront just across the street from the school, her legs spread eagle in the air with her panties swinging around one ankle as the hulking bullmastiff—a stray from the neighborhood that Katie had worked diligently to butter up over the last few weeks—pounds mercilessly into her tight cunt like she was little more than a needy bitch in the throws of heat.</p>
<p> </p>
<p>No, not the first time. And certainly not the last.</p>
<p> </p>
<p><em> "U—ugh! Ugh, fuck! F-fuck, yeah! Good boy, good boy, good boy—f-fuck me harder!" </em> Katie sobs through gritted teeth, hot tears streaming down her cheeks and streaking her cheap dollar-store mascara in the process. The hound pants hard, his heavy, hefty balls smacking against the teen's ass with bruising force.</p>
<p> </p>
<p>Mary's cheeks grow warmer. She averts her gaze with an impatient huff. It's overcast today and the coastal breeze bites at the exposed skin of her thighs and fingers. It does little to deter her sister though, Mary guesses, as she tugs the sleeves of her cardigan down over her knuckles and fusses with the hem of her uniform skirt.</p>
<p> </p>
<p><em> "H-Hurry up, Katie." </em> Mary mumbles anxiously. She shifts her weight from one foot to another and repeatedly glances behind herself to make sure no one is coming. The laughter and chatter of their schoolmates making their way to the courtyard  just a few metres away keeps her on edge.</p>
<p> </p>
<p>"<em> I need more </em>," Katie weeps, and it's a desperate sound. Possessed almost, like a starving creature who eats and eats and eats but can never feel full. She slaps her swollen clit repeatedly with enough stinging force to make Mary flinch but her sister only cries harder as a spoiled child would and pushes her fingers into her asshole.</p>
<p> </p>
<p>The hound's cock is huge. It's thick, bulbous and angry, and Mary watches it threaten to turn her sister's needy cunt inside out with how it stretches her to the limit, and how her wet pink labia clings onto the throbbing shaft like a too-small, too-tight sleeve. Yet Katie is lost in her fervour, <em> mad </em> with it, wrapping her arm around the bullmastiff's frame as her legs kick out in a violent spasm and suddenly she goes taut. Taut as a bow, body rigid and green eyes rolling back in her skull.</p>
<p> </p>
<p><em> "Ghhk—!!" </em> She chokes. For a moment Mary panics. The bullmastiff carries on using his hole regardless, uncaring of the state of his bitch and concerned with little else but reaching his end. Mary considers racing forward to try and pull the hound from her sister but then Katie spasms again, another sharp jolt followed by a warbling, drowning gasp and then, and then—</p>
<p> </p>
<p>She hears the sound of Katie cumming before she registers the sight of it. It's wet patters on concrete followed by a violent gush and suddenly Mary is jumping back to avoid her shoes getting wet, watching on in a sort of haze-like awe as the hound's powerful ruts fuck her sister's juices out of her in messy fanning sprinkles. The school bell's ring drowns out Katie's screaming but Mary can hardly hear either through the sound of her own heartbeat, through the blood rushing in her ears and her suddenly laboured breathing.</p>
<p> </p>
<p><em> 'Katie has always been like this' </em> , she thinks as she watches her older sister dig her fingers into her own scalp and tug at her hair in fistfuls through the onslaught. <em> 'Insatiable and hungry and wrong.' </em></p>
<p> </p>
<hr/>
<p> </p>
<p>
  <em> "Don't tell mom and dad", she whispered on the living room sofa, the sound of the TV drowning out their parents' arguing from the kitchen. Two fingers to spread her folds apart and one hand to drag the remote up and down her pussy, the ridged rubber buttons grating against her clit. </em>
</p>
<p> </p>
<p>
  <em> "... Okay." Mary whispered, and hugged the cushion tighter. </em>
</p>
<p> </p>
<hr/>
<p> </p>
<p>
  <em> "D-don't tell m-mom and dad!" She moaned, her panties around each ankle and cunt crushed against the corner of the rumbling washing machine, feet dangling off the ground. </em>
</p>
<p> </p>
<p>
  <em> "O-okay …" Mary murmured, and worried her bedsheets between her fingers. </em>
</p>
<p> </p>
<hr/>
<p> </p>
<p>
  <em> "D—d—ugh! Ugh! Don't t-t—uh! Uhn! Tell m-mom and d—dad!" She sobbed from the stool in the kitchen, feet braced on the island counter and two hands wrapped around the thick rolling pin that she forced in and out of herself violently, gut lurching with the effort it took to impale herself, tears streaming down her face like it was too much yet not enough, never enough, never enough. </em>
</p>
<p> </p>
<p>
  <em> "O-okay." Mary stammered, and reached up on her tiptoes to slip her dishes into the sink. </em>
</p>
<p> </p>
<hr/>
<p> </p>
<p>
  <em> "Don't tell mom and dad~" Katie giggled in the garden by the swingset, two digits deep in her little sister's snug pussy, fingering her in quick, erratic little tugs as her pebbled clit dragged against her palm. </em>
</p>
<p> </p>
<p>
  <em> "H—hah! Ah! O-o—okay! Okay! Uhn! Uh! Okay!" Mary whimpered in feverish delirium, knuckles white with their grip on the chains. </em>
</p>
<p> </p>
<hr/>
<p> </p>
<p>
  <em> "DON'T—HAH! UHN! D-DON'T TELL—DON'T TELL MOM!" Katie moaned between her slurred laughter and animal panting, hands and knees on their parents' bed as their father fucked into her from behind, one hand fisted in her hair to drag his daughter back down on his cock again and again. The bedroom smelled of hard liquor, an empty bottle in her hands and a half-filled one stuffed in her ass, sloshing back and forth with every thrust and burning her up from the inside in the best way. </em>
</p>
<p> </p>
<p><em> She </em> <em> drooled like a dog in heat, tongue lolled out and mouth pulled into a euphoric, drunken grin. Their father tangled his other hand in her hair and shoved her face-down into the mattress roughly, too far gone and too drunk and too bewitched to care for her muffled screaming. He pummelled into his daughter as if she were meat. Just meat. Like a dollar whore born to be used. Even as her writhing grew weaker and weaker and her screams died out with asphyxiation he did not relent, only stopping to bottom out with a low groan to dump his seed into her unconscious body. </em></p>
<p> </p>
<p>
  <em> "Okay." Mary panted quietly from the doorway, rubbing her soaked underwear in fast circles as her father pulled out only to yank the scotch out and line his half-hard cock to her asshole. </em>
</p>
<p> </p>
<hr/>
<p><br/>She doesn't realise she's cumming until the dog howls. Only then does she register that it's no longer their father filling Katie with seed but the dog, and that she's cumming with her fingers inside of herself watching its fat knot swell out and plug her sister who squirms in blissful, pained euphoria.</p>
<p> </p>
<p>Silence stretches out between them with the chatter of their peers dying off in the distance and only their laboured breathing to fill the void. Katie then reaches down between herself to start rolling her clit.</p>
<p> </p>
<p><em> "I'm not gonna make it in today," </em> she moans. <em> "Tell them … mhm … t-tell them I'm sick." </em></p>
<p> </p>
<p><em> ".... Okay." </em> Mary replies breathlessly, and ducks away with trembling knees to make it to class before role call.</p>
  </div><div class="fff_chapter_notes fff_foot_notes"><b>Author's Note:</b><blockquote class="userstuff"><p>So ... yeah. Ya know. Sometimes something unholy takes over me and I have the urge to write debauchery. I don’t know if I’ll continue this, it depends on the reception, but I got a lot of ideas for these gals so let me know if you enjoyed it. I might be open to suggestions!</p></blockquote></div></div>
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